On a Cisco router running in ROM monitor mode you issue the command confreg 0x2142. What effect does this configuration register value have the next time the router is reloaded?

Introduction / Context:
This operational question focuses on the Cisco configuration register and how it can be used during password recovery and troubleshooting. The confreg command is issued in ROM monitor mode to change how the router behaves when it boots. Understanding the meaning of common configuration register values such as 0x2102 and 0x2142 is essential for field engineers.

Given Data / Assumptions:
- The router is in ROM monitor mode, where low level commands such as confreg are available.
- The administrator sets the configuration register to 0x2142.
- The question asks what happens on the next reload after this register value is set.
- We assume that there is a valid startup configuration stored in NVRAM before the change.

Concept / Approach:
The configuration register controls various boot time behaviors, including where to look for the startup configuration. The default value is typically 0x2102, which instructs the router to load the IOS image from Flash and then read the startup configuration from NVRAM. Changing the value to 0x2142 sets a specific bit that tells the router to ignore the startup configuration in NVRAM during the next boot. This behavior is especially useful for password recovery because it allows the router to come up with a clean configuration while preserving the original startup configuration file.

Step-by-Step Solution:
Step 1: Recall that 0x2102 is the default configuration register that loads both the IOS and the startup configuration.Step 2: Understand that 0x2142 modifies the behavior so that the router still loads the IOS image but skips applying the startup configuration.Step 3: Recognize that when the router boots with 0x2142, it will enter the initial configuration dialog or user mode with no existing configuration active.Step 4: The original startup configuration remains in NVRAM and can be copied into the running configuration later as part of password recovery.Step 5: Conclude that the main effect is to bypass the startup configuration during boot.

Verification / Alternative check:
In the standard Cisco password recovery procedure, one of the documented steps is to change the configuration register to 0x2142, reload the router, and then later copy startup config to running config after setting a new password. This documented workflow confirms that the purpose of 0x2142 is to ignore NVRAM startup configuration during the boot process rather than perform a full reset or clear flash memory.

Why Other Options Are Wrong:
Simply restarting the router is not unique to 0x2142 and does not describe the particular effect of this value. Forcing the router to boot into ROM monitor mode every time is associated with different configuration register bits, not with 0x2142. Displaying the enable secret password on the console is not performed by confreg; Cisco devices do not reveal this information directly. Clearing flash and reloading the IOS image is a destructive operation unrelated to the configuration register value in question.

Common Pitfalls:
A common mistake is to believe that 0x2142 erases the startup configuration, which is not true; it merely instructs the router to ignore it during boot. If engineers misunderstand this, they may fear losing configurations during password recovery when the configuration actually remains safe in NVRAM. Another pitfall is confusing different register values and forgetting to return the register to 0x2102 at the end of the recovery process, which can cause future boots to ignore configuration unexpectedly.

Final Answer:
Setting the configuration register to 0x2142 causes the router to ignore the startup configuration in NVRAM during the next boot so that existing settings can be bypassed.